Recycling Treated Municipal Wastewater for Industrial Water Use

5.5 Storage System Costs
TM3: Recycled Wastewater System Components and Costs
Recycling Treated Municipal Wastewater for Industrial Water Use
Reclaimed water storage is defined as the difference in the diurnal demand and
wastewater flow. While most WWTPs have a consistent diurnal pattern that varies
during the weekdays and weekend, reclaimed water demand will vary with the
customer or set of customers. For this study, it is assumed that 50% of the water
volume produced per day will be stored. Additional storage that may be required by
individual customers and located at the customer’s sites was not considered in this
analysis.
Storage is assumed to be provided in an underground concrete tank, for which the
unit cost of construction is estimated to be $1.70/gallon of the storage. As indicated in
Figure 7, the capital cost of storage is $850,000 per mgd of the annual average
reclaimed water demand. When included into the cost of service, storage adds about
20 cents to the total system cost to produce 1000 gallons. Storage costs equate to about
20% of the cost of service for a 2 mgd supply pumped 5 miles.
Capital Cost, $Million
30
25
20
15
10
5
0
0 5 10 15 20 25 30
Reclaimed Water Flow/Demand, mgd
Figure 7. Storage Capital Costs
5.6 Alternative Water Reuse System Costs
5.6.1 Overview
Six levels of reclaimed water quality were evaluated to estimate the costs to treat and
distribute reclaimed water to a range of industries. The costs were developed with the
same cost model used to establish the base system costs. The treatment process train
was the only system component modified from the base system to estimate the
alternative water quality supply costs.
Water quality classifications are defined by the additional treatment provided over
the base system and are referred to as Tertiary 1, 2, 3, or 4. There are three Tertiary 4
classifications, each dependent on which process follows reverse osmosis: granular
activated carbon (GAC), ion exchange (IE), or ultraviolet radiation (UV) with or
without hydrogen peroxide (H2O2).
Craddock Consulting Engineers 35
In Association with CDM & James Crook
TM3-Component&Costs_0707